Heat treating furnace having double-ended chain conveyor



c. T. HNNM ET Al. 2,898,101

Aug. 4, 1959 HEAT TREATINGV'FURNACE HAVING DOUBLE-ENDED CHAIN CONVEYORFiled Dec. 5, 1956 2 Sheets-Sheet 1 INVENTORS. C. 7.- HHN/VUM Aug- 4,1959 c. T. HANNuM ErAL 2,898,101

HEA'L` TREATING FURNACE HAVING DOUBLE-ENDED CHAIN coNvEYoR Filed Deo. 5.A'195e 2 sheets-sheet 2 INVENTORS F@ 5 c///vA/z//v BY H. M THR/4MM@AA/@Af assignors to Surface Combustion Corporation, Toledo, Ohio, acorporation of Ohio Application December 5, 1956, Serial No. 626,488 6claims. (c1. 26a-4) This invention pertains to a conveyor `forheat-treating vfurnaces and more particularly to a chain conveyor forthe same with `means associated therewith for pushing Vand pulling thework to be heat-treated.

The atmospheric batch-type furnace with alvestibule outside thecharge-discharge opening and which contains a quench tank below theopening is extremely popular l;in the heat-treating eld. t Thisl isprincipallyV due to` the fact that this type of furnace is compact andcan be used with a variety of rheat-treating processes includingcarburizing, nitriding, hardening, carbon restoration, and :annealingSuch furnaces, however, present a problemconcerning 'cadequate means forcharging and: discharging the work `since the work must be charged anddischarged through xdzhe-V same openingand the area over the quench tankYmust be kept` unobstructed for vertical movement of thequench-elevator; A commonly used apparatus consists ofone or Lmoreretractable hooked rods extended through -tfhe"vestibu'le opening tograsp thefwork tray and-which are 'usually adequate for manual operationbut' are not #readily adaptable 'for automatic operation. Also, the-rodslrequire that'a considerable area of clear'space be @maintained infront of the furnace so that the retraction of the rods will beunobstructed. Other types of chargerfdischarge apparatus have also beentried Y with-*only imoderate'degrees of success.

` lAccordingly, a new Vand novel :conveyor hasl been de- L"velopedthat-operates from the front and/or rear end Lof the furnaceautomatically. lThenew conveyor has :automatic releasable means forengaging and 'disengaging fthe trays carrying the work and furtherdoes'not obstruct the operation of the quench elevator. i

For further 'consideration of the invention, its ad l"vanta'ges" andnovelty, refer to the following portion of the specification, theappended claims, and the accompanying'drawing. t

` In thedr'awing: v A

Figure l is a cross-sectional view-on line 1-1 of Figure 2 of apparatus`embodying the invention,

"I Figure 2 a cross-`sectonal view onV line-2 2 of Figurefl,` Figure 3is an tion: of Figure 2, and

Figures 4 and 5 are detailed views ofother portions of the apparatus ofFigures 1 and 2.

. Referring to the drawing, the furnace 11 comprises a heating chamber12 and vestibule chamber 13, the former being formed by refractory wall`14 and the latter by metal wall 15. Chamber 12 is heated by radianttubes 16 placed on both sides of the roller conveyor 17 which consistsof two lines of rollers. 18 supported in holders 20 on platform 21. Atrough is formedbetween the holders by platform 21 Y and members 23 inwhich chain 22 and cart 36 rests. The chain is preventedl from bucklingdownwardly by platform v21 and upwardly by ;members 23- j j v j Chain 22comprises wheels 24,"pairs of which are conenlarged, `cross-sectionalview'of a por? -ofl chain 22' is pushed upwardly by a cam l62 located ataxles in a linear manner.

2,898,101 Patented ug. 4, 1959 2 nected by 'axles 25; links 26 and 27interconnect the sprocket 28 driven ,through motor 29 and reducer 30outside the rear end of chamber 12.' The outer'end Aof the chain isdirected by guides 31 into an elongated receptacle 32, forming volume33,-1ocated beneath the chamber 12. Receptacle 32 communicates with ahousing 34 forming chamber 35 encompassing'sprocket'iZS. The entirechain is thus enclosed in a gas-tight space comprising chamber 112,volume 35, and volume 33, and an atmosphere gas maythu's'be maintainedin chamber 12 with a minimum of leakage.

Apush-pull cart 36 is attached to the rupper end of chains 22 throughlink 39 and comprises a cast body 37 to which three pairs of wheels 38are' attached. The body has a projection 40 which is of'suticient heightto ucontact a tray on rollers 18. lThe body also has a hori- -zontallyextending arm 41 to which a rotatable dog 42 jisattached by pivot 43.The lower end of dog 42V is heavier so as to maintain the opposite Vendin an upward,

-engageable position with a projection ofthe tray except 'when the lowerend is moved upwardly by cam 44. In- "stead of a projection, a recess orhole in the tray may be vprovided into which the upper end of the dogprojects.

Cam 44 is located on Vthe rearward end of a platform v51 which islocated below a second platform 52, both containing rollers 18 and beinginterconnected by bars 5,3,.3. The unit forms an elevator which isvertically moved by. a hydraulicI or 'pnuernatic piston 54 and directedby guides 55 and'56 into quench tank 57.

From this elevator, work may be removed through vestibule vdoor 58 bymeans of manually operated hooked rods or by a second chain similar tothe one at the rearward end ofthe furnace. The @chain 22' is identicalto chain 22 except Vbeing somewhat shorter in length. It is driven byanother sprocket 28 and rides in a similar trough. The cart 36 and itscomponents are likewise similar. The chain is guided here, around thesprocket, by a fabricated metal sheet 60 and has a receptacle 61 whichneed not be gas tight. The lower end of dog 42 the forward end of upperplatform 52.

In operation, ay tray of` work to be heat-treated is placed on charge.table 63 and chain 22 4is moved forwardly. Projection 40 of the chainthencontacts the forward edge of the tray until it reaches the end ofits forward vtravel near lthe forward end. of platform 52 '1 which islowered into alignment with the roller's'lS on fthe charge table and in'the heating chamber.

At this point, the chain is retracted, leaving the tray'on platform 52.`The upper end of. dog42 is depressed by cam 62 so that the dog cannotcatch on the tray and withdraw it. Door 58 is then closed, door 64opened, andv chain 22 advanced toward the forward end of the furnaceuntil dog 42 engages thetray. Thischain is then withdrawn tothe rear endof the heat treating chamber, leaving 'the tray properly positionedon'rollers 18 inthe chamber. At ,the end of the treating period and'with door 64 again opened, chain 22 is advanced Iand the tray pushedback into vestibule 13 by means of' projection 1,40.' The tray thenrests on platform 51'which lhas `been raised. Chain 22 is againwithdrawn and is free lof 4the tray since the upper portion of the dog42 is lowered by means of cam 44. The platforms are again lowered sothat the work is immersed in the quenching medium and platform 52 isagain at the level of the charge table i and furnace hearth. While thework is being quenched another tray of work may be charged into thefurnace if desired. Platform 52 is raised after the'quenching period isoverand the tray is discharged from platform 51 by chain 22 and dog 42'which remains in its upward The chain meshes with a position when thechain is advanced and engages the tray when the chain is reversed.

It may be seen through the above illustration that the inventionprovides a quick, efficient means for transporting work in, into, andout of a furnace and allows a tray to be charged while a previouslyheat-treated tray of work is being quenched. Maximum output may thus beachieved with a given furnace.

The foregoing has been intended to serve in an illustrative and not alimiting sense, the only limitation being in accordance with the scopeof the claims appended hereto.

We claim:

l. A heat-treating furnace comprising: a heating chamber; means forheating said chamber; a door controlled opening at the front end of saidchamber; a quench tank outside said chamber and below said opening;iirst conveying means for slidably supporting work in chamber; a troughin said chamber parallel to the direction of travel of the work to beheat treated; a quench elevator having an upper position and a lowerposition, the latter being in said quench tank; second conveying meansfor slidably supporting work on said elevator, said second means beingaligned with said first conveying means when said elevator is in itsupper position; a conveying chain extending through an opening in theback of said chamber, with a rst end in said chamber and a second endoutside said chamber, said rst end being located in said trough; asprocket located outside the back end of said chamber and enmeshing saidchain between its ends; a projection on said first end and extendingabove the level of the conveying means; a releasable dog associated withsaid rst end and spaced from said projection in a direction toward thefront end 'of said chamber, one end of said dog extending above thelevel of said conveying means when in its normal position; and a cam onsaid elevator for releasing said dog, whereby said cam will lower thatend of said dog extending above said conveying means when said chain isdriven by said sprocket toward the charge end of the furnace and releasesaid dog from engagement with a tray when said chain is withdrawn.

2. Apparatus according to claim l characterized by a gas-tight housingoutside said chamber which encloses said sprocket and that portion ofsaid chain outside said chamber.

3. In a heat-treating furnace having a heating chamber; means forheating said chamber; a door controlled opening at the front end of saidchamber; a quench tank outside said chamber and below said opening;first conveyor means for supporting and moving work in said chamber; aquench elevator having lower and upper platforms which are parallel andin spaced relationship with one another; means for moving said elevatorin a vertical manner between an upper and lower position, said lowerplatform being aligned with said conveyor means when said elevator is inits upper position and said upper platform being aligned with saidconveyor means and said lower platform being in said quench tank whensaid elevator is in its lower position; the improvement which comprises:guide means adapted to be located in said chamber parallel to thedirection of travel of work to be heat treated; a conveying chainextending through an opening in the back end of said chamber, with a rstend in said chamber and a second end outside said chamber, said rst endbeing associated with said guide means which guides and prevents thechain from buckling; a sprocket located outside the back end of saidchamber and enmeshing said chain between its ends; a projection on saidrst end and extending above the level of the conveying means; areleasable dog associated with said rst end and spaced from saidprojection in a direction toward the front end of said chamber, one endof said dog extending above the level of said conveying means when inits normal position; means for reversibly driving said sprocket; and cammeans attached to the rear portion of said lower platform for releasingsaid dog from engagement with a tray of heat-treated work when said cammeans is in contact with said dog. 5 4, Apparatus according to claim 3characterized by a charge table located on the side of said quench tankopposite the heating chamber; second conveyor means on said charge tablealigned with said first conveyor means; second guide means parallel tothe direction of travel of work on said charge table; a second conveyingchain, the iirst end of which is associated with said second guidemeans, said second chain being guided and prevented from buckling bysaid second guide means; a second sprocket located adjacent the front ofsaid charge table and enmeshing said second chain; second means forreversibly driving said second chain; a second projection on said firstend of said second chain and extending above the level of said secondconveyor means; a second releasable dog aflxed to said first end of saidsecond chain and spaced from said projection toward said chamber, oneend of said dog extending above the level of said second conveyor meanswhen in its normal position; and second cam means attached to theforward portion of said upper platform for releasing said dog fromengagement with a tray of work to be heat-treated when said second cammeans contacts saidsecond dog.

5. A heat-treating furnace comprising: a heating charnber; means forheating said chamber; a door controlled opening at the front end of saidchamber; a vestibule outside of and attached to the front end of saidchamber; conveying means for slidably supporting work in said chamber;guide means located in said chamber par allel to the direction of travelof work to be heat treated; a double-ended conveying chain extendingthrough an opening in the back of said chamber with a first end in saidchamber and a second end outside said chamber, said rst end beinglocated in said guide means; a sprocket located outside the back end ofsaid chamber enmesh ing said chain between its ends; a projection on thefirst end of said conveying chain to engage work on the conveying means;a releasable dog `attached to the iirst end of said conveying chain andspaced from said projection in a direction toward the front end of saidchamber, said dog having a normal Work engaging position, and meanswithin said vestibule for selectively releasing said releasable dog,said means being externally operable, whereby when said chain isadvanced from the rear of the heating chamber toward the vestibule todischarge work from .the chamber said means may be operated to releasesaid dog and the chain can be returned to said chamber leaving the workin said vestibule, and when said chain is advanced from the heatingchamber into the vestibule to extract work from said vestibule, thereleasable dog will remain in its normal position to engage the work sothat the work will be pulled from the vestibule into said chamber whenIthe chain is returned thereto.

6. Apparatus according to claim 5 and comprising an elevator locatedwithin said vestibule, said elevator having lower and upper platformswhich are parallel and in spaced relationship with one another;externally operable means for moving said elevator in a vertical mannerbetween an upper and lower position, said lower platform being alignedwith said conveying means when said elevator is in its upper positionand said upper platform being aligned with said conveying means whensaid elevator is in its lower position; and wherein said means forreleasing said releasable dog comprises a cam attached to the rearportion of said lower platform whereby when said chain is advanced fromthe rear of the heating chamber toward the vestibule with the elevatorin its upper position, the cam will contact and release said releasabledog, and the chain can be returned to said chamber leaving the work insaid vestibule, and

when said chain is advanced from the heating chamber into thevestibulewith the elevator in its lower position, the releasable dogwill remain in its normal position to engage the work so that the Workwill be pulled from the vestibule into said chamber when the chain isreturned thereto.

References Cited in the le of this patent UNITED STATES PATENTSHollander Feb. 16, 1909 6 Lister July 24, 1923 Ipsen Oct. 28, 1952 IpsenMay 19, 1953 Dow May 19, 1953 Leftwich July 28, 1953 Holcroft Feb. 16,1954 Ipsen June 15, 1954 Joy Sept. 6, 1955 Ipsen May 29, 1956 WingateJan. 1, 1957

